Control arrangements and mechanisms for pivotable devices



Dec. 15, 1964 R. G. LE TOURNEAU 3,161,072

CONTROL ARRANGEMENTS AND MECHANISMS FOR PIVOTABLE DEVICES Filed on. 2, 1962 NIL-5i INVENTOR. 750% 6116 /EMVWWZM nited States Patent 3,161,072 (IGNQL ANGER TENTS AND MEQHANEMS FOR PTVQBTABLE DEVTCES Robert G. Le'lourneau, R0. Box 2307, Longview, Tex.

Filed Get. 2, 1962, Ser. No. 227,877

4- Claims. (Cl. 74--42Z) My invention relates to improvements in control arrangements and mechanisms for .pivotable devices, and more particularly to such arrangements and mechanisms for a pivotable device mounting a work tool and wherein a powered rack is employed.

Many structures which are disposed to pivot about axes may be suitably moved and controlled by rack and pinion mechanisms. In some earthwork-ing machines, for example, it is not unusual for pivotable mechanisms, such as dozer blades and aprons for scraper buckets, to be actuated and controlled by a length of rack and a powered gear reduction having an output pinion engaging the rack. The length of rack is connected at one end to the pivotable structure and is straight. This makes it necessary to provide a pair of back-up rollers journaled so as to bear against the back surface of the rack Opposite the region of the intermeshing rack and pinion. Furthermore, the back-up rollers must be mounted so as to allow some pivoting movement about the pinion axis. While this manner of controlling pivotable structures is disclosed in the prior art, it is recognized that it is not entirely satisfactory and that new and useful improvements may be made therein.

Accordingly, it is the general object of my invention to provide improved control arrangements and mecha nisms for pivotable devices.

Another object of my invention is to provide, for controlling a pivotable device, a mechanism employing a rack and only a single back-up roller.

Another object of my invention is to provide, for controlling a pivotable device, a mechanism employing a rack, that is simpler and more economical than those heretofore available.

More particularly, in accordance with the present invention, there is provided an arcuate length of rack having one end connected to a pivotable device with the pitch line of the rack teeth being an arc of a circle having its center at the pivot axis of said device. A gear reduction is fixedly mounted on a support structure adjacent the rack and has an output pinion engaging the rack. A single hack-up roller is fixedly mounted in radial alignment with the output pinion and the pivotable device so as to rollab-ly engage the back surface of the rack.

For a further understanding of my invention and further objects, features, and advantages thereof, reference may now be had to the following description taken in conjunction with the accompanying drawing in which:

FIG. 1 is a schematic fragmentary plan view of the front end portion of an earthworking machine employing a control arrangement and mechanism for a pivotable device in accordance with a preferred embodiment of my invention; and

FIG. 2 is a schematic fragmentary side elevational view of the front end portion of the machine of FIG. 1, in one operative position.

Referring now to the drawing, in FIG. 1, there is shown the front end portion 11 of an earthworking machine having a main frame 13, which is supported at the front end by a pair of electric motor-driven wheels 15, 17 and an axle 19. A dozer blade 21 extends transversely in front of the machine and is provided at the extremities thereof with support arms 23, 25. The ends of the support arms are provided with sockets 27, 29 each of which engages a respective ball 31, 33. These balls are fixedly mounted on the extremities of support structures 35, 37 projecting artists Patented Dec. 15, 1964 outwardly from the sides of the main frame 13 a distance which is suiiicient to provide suitable clearance between the arms 23, 25 and the respective Wheels 15, 17. The support arms Z3, 25 are provided with a pair of tubular braces 39, 41, lying in parallel vertical planes and connecting the upper edge of the blade 21 and the upper surface of the arms 23, 25. A similar pair of tubular braces 43, 45 are disposed in a common horizontal plane and connect the back surface of the dozer blade and the inner vertical surface of the arms 23, 25.

The dozer blade 21 is provided with a curved'front surface 47, to the-lower edge of which is attached a cutting edge 49. A pair of hinge side plates 51, 53 are fixed to and extend rearwardly from the central lower back edge of the blade 21. A length of arcuate rack 55, having a goose-neck bend 57 at one end, is journaled between the hinge plates 51, 53 on a pivot or hinge pin 59. The

. rack 55 is formed to the arc of a circle having its center on the center line connecting the balls 31, 33, which is the axis of rotation of the blade 21. The rack teeth are disposed rearwardly, preferably, as shown in FIG. 2. A gear reduction 61, which is driven by an electric motor 63, is fixed to one end of a suitable support structure that is rigdly connected, at the other end, near the mid point of the axle 19. The gear reduction 61 is provided with an output pinion 67 which engages the teeth of the arcuate rack 55. A single back-up roller 69 is mounted on a shaft 71 which is journaled in a pair of plates 70, 72 that are suitably fixed to the gear reduction 61. The single back-up roller 69 is not pivotable, but is so mounted in the side plates 7% 72 that it is in continuous rollable engagement with the back of the arcuate rack 55.

An operators cab and control station 73 is conveniently located centrally between the front wheels and in an elevated position above the main frame 13.

In order to describe the manner in which the control mechanism operates, reference is made to FIG. 2. In the operative position shown, the blade 21 is disposed so that the cutting edge 49 is in an earth-engaging position. The weight of the blade, rack and a portion of the support arms is upheld by the support structure 65 through the pinion 6'7 and the gear reduction 61. The single back-up roller 69 rollably engages the back surface of the rack and maintains the pinion 67 in positive engagement With the rack teeth.

Whenever it is desired to raise or lower the relative height of the blade and cutting edge, it is necessary for the operator only to actuate the motor-driven gear reduction 61. The pinion, thereupon, moves the rack in the desired direction relative to the gear reduction. The rack being formed to the arc of a circle, having its center on the pivot axis of the pivotable device, will be in continuous engagement with the output pinion. A feature of the present invention is that, with such an arcuate rack, only a single, fixed, non-pivotable back-up roller is required. This is in contrast to prior art systems which use a length of straight rack and, of necessity, a pair of pivotable back-up rollers. In the mechanism of the present invention, the single non-pivotable back-up roller is disposed in radial alignment with the output pinion and the pivotable device. The only purpose of the single roller is to react in line with the outward radial thrust of the pinion when moving the rack. Thus, the single back-up roller maintains the rack and pinion in continuous engagement.

While the drawing illustrates my invention as applied to a pivotable dozer blade of an earthworking machine, it is understood that my invention may be applied to many other types of pivotable devices, such as adjustable angularly disposable blade of a roadgrader, the apron of an earth carrying scraper bucket, and the like. It is evident, also, that my invention has wide applicability as n; a control mechanism for many other and various types of pivotable devices not necessarily related to earthworking machinery.

While I have shown my invention in only one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications without departing from the spirit thereof.

I claim:

1. In an earthworking machine having a main frame and an earth engaging work tool structure pivotably mounted thereon for movement about an axis, a movement control mechanism for such earth engaging structure which comprises: a powered gear reduction mounted on said main frame above said earth engaging structure and having an output pinion; an arcuate length of rack connected at one end to said earth engaging structure and engaging said output pinion; and a single back-up roller journally mounted in a fixed position adjacent said pinion for rollable engagement with the back surface of said rack and disposed in radial alignment with said output pinion.

2. In an earthworking machine having a main frame and a work tool structure pivotably mounted thereon for movement about an axis, a movement control mechanism for such structure which comprises: a powered gear reduction mounted on said main frame above said structure and having an output pinion; an arcuate length of rack connected at one end to said structure and having teeth engaging said pinion, said rack being so formed that the pitch line of the teeth thereof is the arc of a circle having its center on said axis of rotation of said pivotable structure; and a single back-up roller journally mounted in a fixed position adjacent said pinion for rollable engagement with the back surface of said rack and disposed in radial alignment with said output pinion.

3. A control mechanism for a pivotable work tool structure mounted for movement about an axis, which comprises: an arcuate length of rack connected at one end to said pivotable structure and having teeth so arranged that the pitch line thereof is the arc of a circle having its center on said axis; support means fixed relative to said rack teeth pitch line; a powered gear reduction fixedly mounted on said support means and having an output pinion engaging said rack; and a single back-up roller journally mounted in a fixed position relative to said pinion for rollable engagement with the back surface of said rack and disposed in radial alignment with said output pinion.

4. In a machine having a main frame and a pivotable work tool structure mounted thereon for movement about an axis, a movement control mechanism for such pivotable structure which comprises: an arcuate length of rack connected at one end to said pivotable structure and having teeth so arranged that the pitch line thereof is the are of a circle having its center on said axis; support means mounted on said main frame and fixed relative to said rack teeth pitch line; a powered gear reduction fixedly mounted on said support means and having an output pinion engaging said rack; and a single back-up roller journally mounted in a fixed position relative to said pinion for rollable engagement with the back surface of said rack and disposed in radial alignment with said output pinion.

References Cited in the file of this patent UNITED STATES PATENTS 

1. IN AN EARTHWORKING MACHINE HAVING A MAIN FRAME AND AN EARTH ENGAGING WORK TOOL STRUCTURE PIVOTABLY MOUNTED THEREON FOR MOVEMENT ABOUT AN AXIS, A MOVEMENT CONTROL MECHANISM FOR SUCH EARTH ENGAGING STRUCTURE WHICH COMPRISES: A POWERED GEAR REDUCTION MOUNTED ON SAID MAIN FRAME ABOVE SAID EARTH ENGAGING STRUCTURE AND HAVING AN OUTPUT PINION; AN ARCUATE LENGTH OF RACK CONNECTED AT ONE END TO SAID EARTH ENGAGING STRUCTURE AND ENGAGING SAID OUTPUT PINION; AND A SINGLE BACK-UP ROLLER JOURNALLY MOUNTED IN A FIXED POSITION ADJACENT SAID PINION 